CO

2

and Energy #2

Jasper Kok

Applied Physics Program Climate science & policy enthusiast Lecture for AOSS 480, Ricky Rood

Outline and review lecture 1

 Lecture 1: Current and past energy use – Historic CO 2 emissions and energy use – Current sources of energy – Energy use and CO 2 emissions of economic sectors – Energy use and CO 2 emissions by end use 10

US energy use by sector

cement and gas flaring 8

gas

6

oil

4

coal

2 0 1850 1900 1950

deforestation

2000

World CO 2 emissions by fuel and end use

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – – – – ‘Business as usual’  Do we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system?

‘Wedges’ to mitigate climate change Energy supply decarbonization ‘tools’  Energy efficiency  Renewable energies   Carbon capture and sequestration Biofuels Specific ‘wedges’ of mitigation – Externality: energy and water

Key reference

 The ‘wedge’ paper: “A plan to keep carbon in check” by Socolow and Pacala, Scientific American, 2006.

– This is an influential policy-oriented paper on how to reform energy sector while still achieving economic growth – Accessible through http://mirlyn.lib.umich.edu

 On local server: Socolow and Pacala: Keeping Carbon in Check (Scientific American, 2006)

Future energy policy: What are we trying to achieve?

 The 1992 UN Framework Convention on Climate Change was signed by most countries. Stated objective: “to achieve stabilization of GHG concentrations in the atmosphere at a low enough level to prevent

dangerous anthropogenic interference with the climate system”

The green countries have signed UNFCCC!

 This should be done in a time frame sufficient: – to allow ecosystems to adapt naturally to climate change – – to ensure that food production is not threatened to enable economic development to proceed in a sustainable manner  Does ‘business as usual’ allow this? If not, then what energy policies should we introduce (as a world community)?

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – ‘

Business as usual’



Do we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system?

– ‘Wedges’ to mitigate climate change – Energy supply decarbonization ‘tools’  Energy efficiency    Renewable energies Carbon sequestration Biofuels – Specific ‘wedges’ of mitigation – Externality: energy and water

‘Business as usual’ CO

2

-trajectory path

≈ business as usual

 ‘Business as usual’ has CO 2 emissions growing at current rate (1.5%/year) – Likely end-of-century warming: ~2.3 – 3.4 ºC

‘Business as usual’ End-of-century temperature change

 “Business as usual” (2090-2099) scenario – Global mean warming 2.8 ºC; – – Much of land area warms by ~3.5 ºC Arctic warms by ~7 ºC

Will ‘business as usual’ lead to ‘dangerous’ climate change?

 At > 2 ºC – Ecosystems become threatened – Food supply jeopardized – Abrupt / irreversible changes (could lead to large-scale economic damage)   Many scientists think should prevent >2 ºC warming  EU policy aimed at < 2 ºC warming So what is a ‘safe’ CO 2 trajectory and how do we achieve it?

Likely range of ‘business as usual’ by 2100

CO

2

stabilization trajectory

 Need to stay below ~2 ºC to avoid ‘dangerous’ climate change.

 Stabilize at < 550 ppm. Pre-industrial: 275 ppm, current: 385 ppm.

 Need 7 ‘wedges’ of prevented CO 2 emissions.

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – ‘Business as usual’  Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system – – – –

‘Wedges’ to mitigate climate change

Energy supply decarbonization ‘tools’  Energy efficiency    Renewable energies Carbon sequestration Biofuels Specific ‘wedges’ of mitigation Externality: energy and water

What is a ‘wedge’?

 A ‘wedge’ is a strategy to reduce carbon emissions that grows from zero to 1 GtC/year in 50 years  The world needs to implement 7 of these wedges to prevent ‘dangerous’ climate change  Examples: – Expand wind energy – – Make cars more efficient Reduce deforestation rates

Developing Vs. developed world

 Implementation of wedges would lead to large emission reductions in developed world  Developing world would increase emissions, but less than without carbon constraints

How and where to get the wedges

 Need 7 wedges for 2xCO 2 stabilization  Where and how is most cost-effective to cut CO 2 ?

 Tools wedges use: – Improved energy efficiency – Renewable energies (wind, solar) – Carbon capture and sequestration – Biofuels

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – ‘Business as usual’  Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system – ‘Wedges’ to mitigate climate change –

Energy supply decarbonization tools



Energy efficiency

– – 

Renewable energies



Carbon capture and sequestration



Biofuels

Specific ‘wedges’ of mitigation Externality: energy and water

Efficiency Gains

    The low-hanging fruit!

Essentially three kinds: – End-use electricity efficiency (fluorescent bulbs instead of incandescent bulbs) – Energy generation efficiency (coal plant operating at 60 % efficiency instead of current 40 %) – Transportation efficiency (60 mpg instead of 30 mpg) Efficiency gains are generally cheap mitigation options But will only get so far before cutting into primary energy used for economic activity

Kinds of renewable energy

 Hydro-power – Already widely used - not much potential for expansion  Wind – Abundant and competitive  Solar – – Photovoltaic (PV) Concentrating solar

Renewable energy: Wind

 Probably most promising renewable energy source  Supplies ~1 % of world electricity, ~0.3 % in US Wind energy cost in $/kWh $0.40

$0.30

$0.20

$0.10

$0.00

1980 1984 1988 1991 1995 2000 2005  Is cost-effective against coal and natural gas  Is undergoing very rapid growth (5-fold increase 2000 2007)

Renewable energy: Wind

 Advantages: – Wind energy is relatively mature technology and is cost effective – Can be utilized at all scales   Large wind farms On small agricultural farms – Total theoretical potential of wind energy on land/near shore is 5x current energy consumption  Large potential for expansion

Renewable energy: Wind

 Disadvantages: – Horizon pollution and NIMBY siting problems – Birds…(though this is often over stated – about 1-2 birds per turbine per year) – Wind is intermittent! It can therefore not make up a large fraction of base load (unless effective energy storage)

Renewable energy: Solar

 Essentially three kinds: 1.

2.

3.

Solar heat – Water is heated directly by sunlight – Used cost-effectively on small scale in houses Solar photovoltaic (PV) – Uses photo-electric effect (Einstein!) to produce electricity – Supplies ~0.04 % of world energy use Solar concentrated – Use large mirrors to focus sunlight on steam turbine or very efficient PV panels – More cost-effective than just PV

Renewable energy: Solar

 Advantages: – – Enormous theoretical potential!

Applicable at various scales (individual houses to solar plants) – – Solar heating can be cost effective Economy of scale and/or breakthroughs might reduce costs of PV and solar concentrated  Disadvantages – – PV and solar concentrated are expensive! Currently only cost effective with government subsidies Intermittent – can not make up large portion of base load (except with storage capability)

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – – – ‘Business as usual’  Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system ‘Wedges’ to mitigate climate change Energy supply decarbonization tools  Energy efficiency  Renewable energies 

Carbon capture and sequestration

– – 

Biofuels

Specific ‘wedges’ of mitigation Externality: energy and water

Carbon Capture and Sequestration (CCS)

 Main idea: – Burn fossil fuels for electricity/hydrogen production – – Capture CO 2 ‘Sequester’ it in geological formation, oil/gas field, or ocean floor  This principle is immensely important for future CO 2 mitigation!

– Fossil fuels are abundant and cheap – Renewable energy generally not mature enough to replace fossil fuels – Coal-fired power plants with CCS could provide low-carbon energy at competitive costs  Currently successfully employed in ‘pilot’ projects

CCS: Carbon Capture

 Both conventional and modern types of coal-fired power plants can be adapted for CCS  Conventional coal-fired power plant: – Burn coal in air (much like the old days) – Exhaust gas is ~15 % CO 2 nitrogen and water vapor) (rest is mostly – – Exhaust gas flows over chemicals that selectively absorb CO 2 (‘amines’) The amines are heated to ~150 ºC to give up the CO 2 and produce a (nearly) pure CO 2 gas that can be sequestered.

 Modern coal-fired power plant: – Coal is burned with pure oxygen in a gasification chamber to produce hydrogen and CO 2 – The CO 2 is filtered out and the hydrogen is burned for electricity

CCS: Sequestration

 CO 2 can be sequestered at ~1 km underground, here pressure is high enough to liquify CO 2 , which helps prevent it from leaking  Several options for sequestering CO 2: 1.

Depleted oil/gas reservoirs (can be even be used to enhance oil/gas recovery – reduces costs) 2.

3.

4.

Deep saline (brine) formations CO 2 – these are porous media in which can be stored and dissolve in the salty water Use for coal-bed methane recovery (one of those ‘unconventional’ fossil fuels) Ocean floor (very controversial!)

CCS: economics

 CCS could become cost-effective with future carbon legislation

Biofuels

 Initially hailed as a sustainable substitute for oil  Can help reduce oil imports and improve national security – In US, this is probably main motivation for recent push (“addicted to oil”, Bush’s 2006 State of the Union)  Two main kinds of biofuels:

1.

First generation: 2.

Produced by converting sugar in corn, sugar beets, etc., into ethanol (alcohol)

Second generation:

Produced through “cellulosic conversion” of biomass into sugar, then sugar into ethanol  Climate change impact of different biofuels is very different!

Biofuels – First Generation

  In US, mainly corn-based ethanol – Heavily subsidized by federal government to reduce oil dependence (~$1.90/gallon) Effect on climate change is

negative

: – Energy used in production is comparable to energy content – Significant amounts of N 2 O (a potent GHG) can be produced through fertilizer use – – More carbon would be sequestered by letting crop land lie fallow Raises food prices  Tropical deforestation, which releases more carbon than saved from fuel production over > 30-year period Source: Fargione et al., Science, 2008

Biofuels – Second Generation

  Produced from plants containing cellulose – Cellulosic conversion to sugar is very difficult and expensive! (cows have 4 stomach compartments for a reason…) Second generation biofuels are better for climate change: – – Similar amount of carbon sequestered as fallow cropland But, competition with food still leads to tropical deforestation and net release of carbon!

US 1 st generation biofuel US 2 nd generation biofuel

Biofuels – do they help or hurt?

 In general, biofuels that compete with food will not contribute to mitigating climate change – Direct link between food demand/prices and tropical deforestation  Production of first generation biofuels (directly from food such as corn) is not a solution to climate change and should be avoided!

 Production of second generation biofuels (from biomass) is only helpful if it doesn’t compete with food production (so not grown on cropland) – Second generation biofuels from agricultural waste could play important role, but is currently not cost-effective  In light of these recent results (2007/2008), EU is reconsidering past biofuel mandates and subsidies

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – ‘Business as usual’  Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system – – ‘Wedges’ to mitigate climate change Energy supply decarbonization ‘tools’  Energy efficiency    Renewable energies Carbon sequestration Biofuels – –

Specific ‘wedges’ of mitigation

Externality: energy and water

Where can we create ‘wedges’ in the energy system?

 Power generation (40 %) – This is the ‘easy’ target because of availability of cost effective low-carbon options (wind, CCS)  Direct fuel use (36 %) – This can be ‘switched’ to low carbon electricity

??? ???

 Transportation (24 %) – This is the tough nut to crack!

– Currently no real feasible low carbon alternatives  Lot of infrastructure in place for fossil fuel-based transportation!



How to create ‘wedges’: Power Generation

Several options, each one wedge: – Increase efficiency of coal-fired power plants from 40 to 60 % ($) – Replace coal-fired to natural gas fired power plants ($) – Double nuclear electricity to replace coal-fired power plants ($$) – Use CCS for low-carbon coal-fired power plants ($$) – Expand wind energy 30x to replace coal-fired power plants ($$) – Expand solar energy 700x to replace coal-fired power plants ($$$)

How to create ‘wedges’: Direct Fuel Use

 Several options, each one wedge: – Improve building insulation ($) – Replace natural gas heat with low-carbon hydrogen from wind/coal with CCS ($$$) – (and general switch to electricity heat instead of fuel heat)

How to create ‘wedges’: Transportation

 Several options, each one wedge: – Increase car efficiency from 30 to 60 mpg ($) – More compact world with less travel  5,000 instead of 10,000 miles/vehicle ($) – – Switch to low-carbon hydrogen ($$$) Switch to

sustainable

biofuels  unlike corn ethanol, these must not compete with food production! ($$$)

Outline Lecture 2

 Lecture 2: Future energy use and climate change mitigation – ‘Business as usual’  Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system – – – ‘Wedges’ to mitigate climate change Energy supply decarbonization ‘tools’  Energy efficiency    Renewable energies Carbon sequestration Biofuels Specific ‘wedges’ of mitigation –

Externality: energy and water

Must address climate change without exacerbating freshwater shortage

    Both energy and water are critical resources Many areas already suffer water stress – note Africa, India, China, where greatest population growth is projected to occur Projected to become worse with increasing population, pollution, and climate change – Dry areas are generally projected to become drier.

Must address energy challenge without exacerbating water scarcity

So where is our fresh water used?

 You can take many, many, very long showers for a pound of steak…  Greatly expanding biofuels from ethanol to substitute oil would probably be bad idea…

Class on Thursday

 Ben Santer will be lecturing on Thursday – He’s a well-known climate scientist!

– Few contemporary scientists get their own Wikipedia page… (http://en.wikipedia.org/wiki/Benjamin_D._Santer)